The invention generally relates to an active energy absorbing system for a motor vehicle steering column, and more particularly, to an active energy absorbing system that adjusts the energy absorbing load according to driver and crash characteristics, as the column collapses.
Energy absorbing steering columns on a motor vehicle generally include a housing that translates linearly through a collapse stroke during a collision. A force generated by the driver from an impact with the steering wheel initiates the collapse stroke. The steering wheel housing moves against a resisting force that may be produced by an energy absorber designed to convert a portion of the driver""s kinetic energy into work. The resisting force may be generated utilizing systems currently known in the art, including the plastic deformation of a metal element that is a part of an energy absorbing device.
Generally, traditional energy absorbing devices have a fixed energy absorbing curve which is optimized to protect a given group of drivers, in most cases represented by an average size male driver. To better protect other groups of drivers not belonging to the average male driver group, such as smaller female drivers or large drivers, an adjustable energy absorbing device is needed in the art.
It is, therefore, desirable for an energy absorbing device to be adjustable based upon a given driver size and his position, as well as include variables for the severity of the collision. It is also desirable to use an energy absorbing device that is capable of adjusting in a time frame similar to that of an airbag system. Therefore, to account for the severity of the collision, and act at the same time as an airbag, an energy absorbing device should be capable of adjustment within a few milliseconds of time such that a given load curve can be utilized by the device based on the severity of the collision and the characteristics of the driver.
There is, therefore, a need in the art for an active energy absorbing device that is capable of adjusting to account for the severity of a collision, as well as the characteristics of the driver. Such an energy absorbing system should be able in a few milliseconds such that it has similar response times to that of an airbag deployment.
An active energy absorbing system including a steering column housing that is movable along a collapse stroke. There is also included an energy absorbing device mounted on the steering column housing that exerts a resistance force for resisting movement of the steering column along the collapse stroke. The energy absorbing device includes a base unit and an adjustable deforming member disposed within the base unit. A deformable strap is housed by the base unit and attached at one end to a vehicle structure. The deformable strap engages the adjustable deforming member. An actuator is associated with the base unit and adjusts the adjustable deforming member. A spring attachment member is associated with the base unit and includes a spring attachment member that has an adjustment portion. A spring is attached to the base unit at one end and to the spring attachment member at another. At least one stop is associated with the base unit and is positioned to interact with the adjustment portion of the spring attachment member. The actuator moves the at least one stop in response to a control parameter wherein the adjustable deforming member is adjusted to correspond to an optimized energy absorbing load.